The invention relates to a method for the continuous detoxification of cyanides and cyanide-containing solutions, especially of cyanide-containing by-products and solutions of by-products such as are formed in galvanic, chemical and hardening-technology processes.
It is already known to detoxify cyanide-containing by-products and solutions of such by-products by establishing various chemical reactions, for example, reactions with hypochlorite, thiosulfate, Iron(II) salts, formaldehyde or hydrogen peroxide. These detoxification methods have the disadvantages that they are relatively expensive to perform and that the removal of the reaction products can involve new difficulties, inasmuch as these reaction products may themselves be in part insufficiently non-toxic.
It is also known that cyanides can be rendered harmless by oxidizing them at temperatures above 1500.degree. C. or by oxidizing them using catalytic methods at temperatures above 400.degree. C. The disadvantage of the first method is the formation of poisonous gases; the disadvantage of the second method is the sensitivity of the catalysts to toxic material.
It is furthermore known to detoxify cyanides at temperatures between 120.degree. and 200.degree. C. under pressure, with the reaction being quickly initiated by using catalysts, such as for example cobalt and nickel compounds. The disadvantage of this method resides in the fact that relatively expensive catalysts must be employed, and in the fact that other substances contained in the cyanide-containing byproduct solution may cause an inactivation of the catalysts. If the just-mentioned approach is taken, but without the use of catalysts, the reaction times are excessive.